Skip to content

H HelpMePrep interview notes Search notes /

Home Companies Progress

System design Low-level design DSA

Start here

How to use these notes Delivery framework

Core concepts

Networking basics APIs Data modeling SQL versus NoSQL Indexing Caching Sharding and partitioning Replication Consistency, CAP, and PACELC Consistent hashing Queues and streams Idempotency and retries Rate limiting Back-of-the-envelope estimation Observability Security basics

Key technologies

Postgres Redis Kafka Elasticsearch DynamoDB and Cassandra Object storage CDNs API gateways and load balancers Stream processing ZooKeeper and etcd Vector databases

Patterns

Real-time updates Long-running tasks Contention and locking Scaling reads Scaling writes Large blob uploads Multi-step processes Geo and proximity search Fan-out Deduplication

Worked problems

URL shortener Dropbox Ticketmaster Uber and ride matching Food delivery dispatch News feed WhatsApp-style chat YouTube Rate limiter Web crawler Ad click aggregator Top-K and leaderboards Payment system Job scheduler Typeahead LLM inference serving RAG system Agent evaluation pipeline Talent marketplace matching Expert task routing

Search

Full-text

Search

Searches the built notes in this browser. It is generated at build time, so it works on GitHub Pages without a server.